By Martin Harris.

Automatic Blast Gates: Are They Worth It?

Automatic blast gates are motor driven gates that open when you turn on a tool and close when you turn it off, and most systems start the dust collector at the same time. They are worth it if your gates are mounted out of reach, your collector sits in another room, or you run several tools and keep forgetting to switch gates. For a one or two car garage with a handful of tools and gates you can reach, manual gates plus a remote switch cost far less and do the same job.

This page explains how the common systems sense a tool, what they need for power and wiring, and where the money goes. If you are still comparing plain gates, see my best blast gates roundup. If your main goal is to stop walking to the collector switch, a dust collector remote or current-sensing switch may be all you need.

How automatic blast gates work

Every automatic system has three jobs to do: notice that a tool turned on, open the right gate, and start the collector. The hobby systems do the first job with current sensing. A current sensor watches the power cord of a tool. When the tool draws power, the sensor notices and sends a signal.

iVAC is the brand most small shops run into, and Rockler sells its gates alongside Rockler's own manual Dust Right gates. Here is how the iVAC Pro system works, based on iVAC's product pages and published specifications:

• The sensor. The iVAC Pro Tool Plus clamps onto the power cord of a tool. iVAC's specifications say it detects the magnetic field around the cord when the tool runs, with an adjustable trigger level starting around 0.3 amps. It is powered by a 5 volt USB adapter, so you do not cut into the tool's cord.
• The collector switch. The sensor sends a wireless signal to the iVAC Pro Switch, which the collector plugs into. iVAC lists a radio range of 40 feet between sensor and switch. One Pro Switch accepts signals from up to 8 tools, and it keeps the collector running 5, 15, or 45 seconds after the tool stops so the hose clears.
• The gate. The same signal tells the iVAC Pro Blast Gate to open. When the tool shuts off, the gate closes. Small DIP switches inside each part (tiny on and off switches) set which sensor goes with which gate.

iVAC offers the Pro Blast Gate as a 4 inch metal gate with a plastic enclosure, a 4 inch all metal gate, and a 6 inch all metal gate. Its product page lists a self-cleaning slide, an open or closed indicator, motor overload protection, and an "always open" feature that keeps at least one gate open. The gates can also be run from a handheld iVAC Pro Remote or from a wired toggle cable that you mount near the tool, which helps for a tool that does not plug into a normal cord, or for opening a gate to a floor sweep.

Other automatic gate systems

Ecogate sits at the industrial end. Its Smart Gates have an embedded processor that measures air velocity, air pressure, and air volume in the duct, and they report that data to Ecogate's greenBOX controller. The gates use a 24 volt DC actuator and come in sizes from 2 to 26 inches. Ecogate sells mostly to production shops and other industries, though it also offers standalone gates for shops that need only one.

On the Rockler side, the Dust Right name covers manual gates, including self-cleaning Ready-Mount gates, and a remote switch for the collector. I could not find a Dust Right branded motorized gate. If you see "automatic" near Rockler's gates, it is the iVAC gate Rockler carries.

Some woodworkers build their own systems with current sensing relays, contactors, and small controller boards. That route involves wiring at line voltage, the 120 or 240 volt power that runs your tools. I would only go that way if you are qualified to do electrical work, or you have a licensed electrician build or check the power side.

Power and wiring needs

This is the part people miss when they price out automatic gates. Each iVAC Pro Blast Gate runs on its own 115 volt AC adapter, according to iVAC. That means you need an outlet near every gate. If your gates are up by the ceiling at the wyes, where they belong, you may need new receptacles up there. Plan that before you buy.

• Outlets at the gates. Adding receptacles is electrical work. Have a licensed electrician add them, and skip long chains of extension cords and power strips strung along the duct.
• Collector amp rating. The iVAC Pro Switch comes in a 115 volt, 20 amp version and a 240 volt, 20 amp version. iVAC retailer listings say a collector rated at 8 amps or less can plug into the Pro Switch directly, and one rated at 9 amps or more needs an iVAC contactor. A contactor is a heavy duty relay that handles the motor current while the small switch just tells it when to close. Check the amp rating on your collector's nameplate.
• 240 volt collectors. Many 2 HP and larger collectors run on 240 volts. You need the 240 volt switch and usually a contactor. My dust collector 240V wiring guide covers the circuit side.
• Sensors at the tools. The Pro Tool Plus needs a USB power adapter near each tool, or power from another iVAC unit.

None of this is hard to plan. It does turn a gate swap into a small electrical project, and that is where much of the real cost of going automatic comes from in a garage shop.

Cost compared with manual gates

A manual slide gate is one part. An automatic setup is several parts, and some of them repeat for every tool. Prices change often, so check current listings, but here is what you are buying:

Source: iVAC product pages and published specifications for the Pro Tool Plus, Pro Switch, and Pro Blast Gate. A single motorized gate costs many times what a plain metal slide gate does, and that is before the sensors and switch.

Do automatic gates cost you airflow?

Fully open, a gate is a short section of pipe with a slot in it, and the motor sits outside the air path. The airflow losses that hurt small shops come from long flex hose, tight elbows, and undersized duct. Where automatic gates can help airflow is behavior. They close every time, so you never leave three gates open by accident and split your collector's air three ways. The closing matters just as much as the opening. For the rules on where gates go in the duct, see my guide on how to install blast gates. Automatic gates follow the same placement rules as manual ones.

Who benefits from automatic blast gates

• Shops with gates out of reach. If your main runs along a high ceiling and every gate needs a step stool, automation fixes a daily annoyance.
• Shops with the collector in another room. A collector in a closet, basement, or shed outside the shop already needs remote control. Adding gates to the same system means one action at the tool does everything.
• Shops with many tools. With 6 or more drops, the odds of leaving a gate open go up. A system that closes gates for you keeps the airflow where it belongs.
• Shared shops. If family members, students, or a club use the shop, automatic gates remove a step that new users forget.

Shops that are better off with manual gates:

• One or two car garages with 3 or 4 tools. Put the main on the wall at a reachable height and use manual gates. Add a current sensing switch if you want the collector to start with the tool.
• Shops using one portable collector. If you roll the collector to each tool or move one hose around, there are no branch gates to automate.
• Tight budgets. The money for a few automatic gates can buy a better filter, a cyclone separator, or rigid duct to replace long flex runs, and those changes do more for the air you breathe.

A middle path I like

Start with manual gates at the wyes and a current-sensing switch on the collector, so the collector follows your most used tool. Then add an automatic gate only on the one or two branches that are hard to reach or used most. iVAC gates work in the same system as the Pro Switch, so you can grow into automation one branch at a time. Before any of that, make sure the rest of the system is sound. My dust collection system design guide and my complete guide to small shop dust collection cover the parts that matter more than gates.

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